We went to a HUGE Pirate event. We had a massive ship but not much firepower. For the next event, we're looking to build a canon or two that will fire water balloon over a great distance. While looking for specs I came across your site. (Great Stuff!)

The canons will be mounted to stands and will roll about the ship. Since we'll be on a ship the canons don't have to be entirely portable. Plus they'll look cooler as real canons.

Here's the issue most of the canons I have seen look like they can only fire once and then they need to be refilled. Since we will be on a ship we won't have access to a compressor. However since we will be building stands a pre-filled compressed air tank is possible.

Are there any specs out there for canons that can fire multiple shots using a larger tank? We'd like to make firing these as simple as possible. As few steps as possible

I would suggest a Douchenator, with a bike valve (or similar) in the tank so that it can be fired multiple times.
you would fire, plug in the extra tank to the bike valve, disconnect the extra tank, fire, and repeat.
you could also try a Semi-Auto homemade

I would reccomend any kind of regular WBL mounted on a wheeled stand, with either bike pumps for every one, or pre charged canisters, like the ones that Waterwolf made. And I agree with soakernerd, the canisters would probably be a better idea, especially because the semi-auto WBL only got around 80 feet if I remember correctly. http://www.sscentral.org/homemade/air_canisters.html
-Zeda

Last edited by zeda.beta on Wed Feb 17, 2010 11:32 pm, edited 1 time in total.

Any ordinary water balloon launcher will work, as long as it has a tire valve. To make it look like a real cannon, I would use ABS pipe or spay-paint it black. And yes, WBLs have to be repressurized after fired, but something like a CO2 tank and a regulator could solve that. If you can build a breech, it would also be easy to reload water balloons.

Zeda/Soaknerd,
I like the Douchenator design. If we mount it on a stand with the tank underneath that could work.

Martian,
Definitely going to spray it black. We're thinking a 3" tube inside of a 4" tube. The 4" tube will give the canon some bulk. You mention using CO2. What about a compressed air tank with a regulator on it.

You'll want to go with plan B. Create a pressure chamber about 1ft long (3" diameter) and use a modified sprinkler valve between that and the barrel. 3 ft is a good length for the barrel, which should be 3" but can also be 2" if you're using smaller balloon payloads.

For 2" barrels, there are also a few breeches that can be constructed for faster loading. However, as far as I know, no one has made a breech for 3" barrels and while it's difficult to do, it is probably worth it. I may look into creating one myself in the future since muzzle loading + ramrodding is just ridiculously slow.

After the pressure chamber and barrel, a bike pump provides the most basic method of inputting air. Since you have a good air source however, using a regulator will speed things up, though you may want to have the bike pump attachable just in case air from the tank runs out.

Plan A will not work because, to the best of my knowledge, the regulator will just release air until it's all gone. It's not designed to let out controlled bursts of air.

I don't plan on using a breach system. I am designing a tethered sabot system which will be loaded using a wet towel ram rod. This way the tube gets lubricated and the sabot gets placed. (Plus it's more Piratey!)

Since we'll be firing on other ships I want to use larger balloons so a 3" tube is what we'll use.

A question about using a bike pump. I understand that this may vary based on the size of the chamber and the pump BUT with a standard bike pump and a 1 foot PC. How much pumping does it take to get the required PSI?

Go for the biggest pump that you can comfortably use, and if possible, attatch a pressure gauge to the pressure chamber. Then you can see how many pumps it will take to get to the desired PSI, and be able to use that number on multiple cannons.
-Zeda

We're going to use roughly a four foot piece of 5" PVC (properly rated) to create the outer shell.

We'll use a scuba tank or another compressed air canister rated for a PSI as our source. Which will flow through a regulator and gauge into our pressure chamber.

Inside we'll use 3" PVC for the barrel. The Pressure Chamber and Sprinkler valve will also be contained withing the shell. After running some calculations we can use a 6.75" inch length of 4" PVC for the Pressure Chamber and still have the same volume as a 12" piece of 3" PVC.

A covered button will be mounted on top for firing and the Pressure chamber fill valve and gauge will be mounted so they are visible on the side of the cannon. All PVC will have the required pressure regulations.

I am speechless. That looks AMAZING. However, I am worried about the price. How much can you guys spend on these. you could also probably save some money by using PVC instead of a scuba tank. properly made PVC tanks can withstand a large amount of pressure.

We have a bit of money to throw at this project but even so we'd like to cut some cost. I considered using Large PVC tubes as the air supply however I run into the issue of volume.

Since I will be taking these cannons out on the high seas I need them to be able to fire a lot of rounds before needing to refill the air. A scuba tank is rated at 3000 psi which means with a smaller tank and using the secondary pressure chamber we can get more shots. I doubt a PVC chamber could handle 3000 psi.

We have a few 3000 and 4500 psi paintball tanks around that we are going to use to test the system before we purchase the scuba tanks. Considering they are the most expensive and sort of a variable on this project we'll leave them til last.